Alloy



Patented Mar. 24, 1936 UNITED STATES PATENT OFFICE ALLOY Richard A. Wilkins, Rome, N. Y., assignor to Revere Copper and Brass Incorporated, Rome, N. Y., a corporation of Maryland N Drawing. Application March 2, 1935, Serial No. 9,111

4 Claims. (Cl. 751) My invention relates to alloys. some instances is further desirable to control the Applicant has found that ternary copper-silihardness, tensile strength and ductility of the con-tin alloys with a high copper content and alloy. Silicon tends to increase the tensile the silicon and tin within certain ranges and prostrength at the expense of the ductility, as like- 5 portions possess a high resistance to corrosion. Wise does iron, the latter also acting as a hard- 5 a high tensile strength, and relatively high ducener. Tin in conjunction with silicon'acts to tility or elongation in both the fully annealed and increase both the tensile strength and ductility, cold worked conditions, and that they may be heat as compared to a binary copper-silicon alloy. treated when cold worked markedly to increase Zinc acts to increase the ductility at the expense their yield point without reduction or marked of the tensile strength and hardness. Therefore 10 change in tensile strength, ductility and hard- Zinc when properly proportioned to the silicon, ness. tin and iron acts to control the tensile strength,

It has been found that if iron is added to these ductility and hardness. alloys the hardness may be controlled both by In the imp oved a y. although the preferred varying the amount of iron and by heat treatge of S co s pp o y t0 15 ment of the alloy without materially decreasing below which range the tensile strength and yield the resistance to corrosion or other properties of poin in r n y d r an ove whi h the alloy except a slight increase in tensile range t e a y mes increasingly difiicult to strength at the expense of a slight decrease in cold work, the silicon in many instances may be ductility. as low as 2% and as high as 4.5% and still an 20 Preferably the amount of iron is'such in relaoy be Se u d which Commercially has the tion to the amount of silicon as to cause all the s ed p op t esiron to be in the form of iron silicide, thus avoid- The all y in respect to m of it pr p ies ing the presence of free iron which otherwi e is rather sensitive to iron, and ordinarily the would be present due to the insolubility of the l t er sh ld be mai w n pp i- 25 iron in the copper-base. Any deleterious efiect mately 0.1 and 0.6% so as not deleteriously to aion the corrosion resistance of the alloy due to the eet the p p s f the fl A preferred presence of iron silicide and minute quantities value of 0.25% iron Ordinarily gives excellent reoi free iron is more than offset by the tin. The sults.

iron silicide it has been found apparently dis- The preferred range of tin for the above men- 30 solves in the fully annealed alloy, but precipitates iii ed preferred range Of Silicon is t0 in the heat treated alloy to form needle-like crysbut by maintaining a proper relation between the tals which act to lock together the glide planes of tin and silicon the amount of tin in some inthe crystals of the basic alloy. Thus in the fully stances may be materially increased. As little annealed alloy the hardness is not materially afas 0.25% tin maybe present for all values of sili- 35 fected by the addition of iron to the basic alloy, con from 2 to 4.5%, above which range it is imbut in the heat treated alloy the addition of iron possible economically to cold work the alloy no secures a noticeable hardening eiiect. matter what the amount of tin or zinc. But to Under some conditions of use it may be desirmaintain the alloy hot workable within this range able to increase the hot working properties of of silicon the tin should not exceed roughly 2% 40 the alloy. It has been found that this convenifor all values of silicon up to 3%, and for any ently may be done by adding zinc. Preferably value of silicon above 3% should not exceed a the amount of zinc should not exceed about 2% value roughly represented by a linear decrease in where the alloys are to be used for welding purtin from 2% at 3% silicon to 1.7% at 3.5% siliposes, but otherwise the amount of zinc may be con and to 1.1% at 4.5% silicon. 45 such that the sum of the silicon, tin, iron and The alloys according to the invention may be zinc does not exceed about 10%. In other words, fully annealed by heating them to about 1200 to a maximum of about 7.65% zinc may be employed 1300 F. Within the preferred ranges of 2.75 to when the alloy contains the minimum values 3.5% silicon, 0.25 to 0.5% tin, 0.25% iron, and up hereinafter specified of silicon, tin and iron. As to 2% zinc, all the alloys will have a tensile r little as 0.1% zinc under many conditions will strength of at least approximately 55,000 pounds secure noticeable results. per square inch and an elongation of at least The zinc by improving the hot working propapproximately 65% in two inches. All the alloys erties of the alloy enables many mill products are capable of being cold drawn into rods having to be fabricated more easily of the alloy, and in a tensile strength of at least approximately 55 105,000 pounds per square inch and an elongation of at least approximately 10% in two inches, and are capable of being cold rolled into sheets having a tensile strength of at least approximately 100,000 pounds per square inch and an elongation of at least approximately 5% in two inches. In general the tensile strength will decrease and the ductility increase with the amount of zinc, as above explained, but in no instance will they go below the approximate values above given when the alloys are within the preferred ranges of constituents. All the alloys within the larger ranges above specified will have in the fully annealed condition a tensile strength of at least approximately 50,000 pounds per-square inch and an elongation of at least approximately 60% in two inches, and all are capable of being cold drawn into rods having a tensile strength of at least approximately 100.000 pounds per square inch and an elongation of at least approximately 8% in two inches, and all are capable of being cold rolled into sheets having a tensile strength of at least approximately 90,000 pounds per square inch and an elongation of at least approximately 5% in two inches.

When fully annealed the alloys are capable of at least 50% reduction by cold rolling or-drawing without again annealing them. This enables them readily to be cold worked into articles. By heating the cold worked articles to 500 to 600 F. for 30 to 90 minutes and cooling them in air at room temperature the yield point and hardness will be markedly increased without any material change in the tensile strength or elongation. It will be observed that this heat treatment is performed at temperatures below the full annealing temperatures, or, in other words, is performed at temperatures below the recrystallization temperatures of the copper-silicon-tin-zlnc solution, although performed at the temperatures at which dissolved iron silicide will precipitate as has hereinbefore been referred to.

It will be understood that small amounts of metals other than those herein specified may be added to the alloys for imparting special characteristics when these metals do not destroy such valuable properties of the alloy as it may be desired to retain.

I claim:

1. Corrosion resistant copper base alloys capable of being worked both hot and cold containing copper, silicon, tin, zinc and iron within the following approximate ranges and proportions: silicon 2 to 4.5%, tin 0.25 to 2%, iron 0.1 to 0.6%, zinc appreciable amounts up to 7.65%, balance substantially all copper, the minimum amount of tin being 0.25% for all values of silicon, the maximum amount of tin being 2% for all values of silicon up to 3% and varying between 1.1 and 2% linearly and inversely with the amount of silicon when the latter is between 3 and 4.5%, and the sum of the silicon, tin, iron and zinc not exceeding 10%; the alloys being of relatively high tensile strength and ductility in both the fully annealed and cold worked conditions, and when cold worked from the fully annealed condition being capable of being heat treated for markedly increasing both the yield point and hardness with but relatively vsmall change in the tensile strength and ductility.

2. Corrosion resistant copper base alloys capable of being worked both hot and cold containing copper, silicon, tin, zinc and iron within the following approximate ranges and proportions: silicon 2.75 to 3.5%, tin 0.25 to 2%, iron 0.1 to 0.6%, zinc appreciable amounts up to 2%, balance substantially all copper, the minimum amount of tin being 0.25% for all values of silicon, and the maximum amount of tin being 2% for all values of silicon up to 3% and varying between 1.7 and 2% linearly and inversely with the amount of silicon when the latter is between 3 and 3.5%; the alloys being of relatively high tensile strength and duetility in both the fully annealed and cold worked conditions, and when cold worked from the fully annealed condition being capable of being heat treated for markedly increasing both the yield point and hardness with but relatively small change in the tensile strength and ductility.

3. The alloys according to claim 2 having approximately 0.25 to 0.5% tin.

4. The alloys according to claim 2 having, approximately, 0.25 to 0.5% tin and 0.25%iron.

RICHARD A. WILKINS. 

